Floating roof for tanks



S. G. CANTACUZENE FLOATING Ro'oF FOR TANKS Filed Nov. 21, 1932 Dec. 3, 1935.

Dec. 3, '1935. s. G. cANTAcUzl-:NE 2,023,308

FLOATING ROOF FOR TANKS Filed NOV. 21, 1932 Y 2 sheets-sheet 2 Patented' Dec. 3, 1935 Servan Georges Cantacuzene, Pai'ls, France Application November 2l, 1932, Serial No. 643,'16'3I In Rumania November 27, 1931 1o claims. (on. zzo-ze) This invention ,has forits object a floating roof I adapted to be used within usual tanks, that is to say those having a xed roof.

This :floating rooi:` has the following. advantages: it is much more simple and less costly to manufacture and maintain than those usually employed, it covers the surface of the liquid so as to ensure greater fluid-tightness, it satisfactorily operates on the entire height of the tank up to complete exhaustion of the liquid contained in the latter, it is easily applicable to all tanks of known type without necessitating any important modification of the same, and, nally, it allows of easily cleaning the bottom of the tank.

A form of carrying out the subject-mattei' of the invention will be described hereinafter, by Way of example only, with reference to the ac= companying drawings, in which:

Figs. i and 2 are respectively a vertical section and a horizontal section above the floating roof.

Fig. f3 is a partial vertical section;

Fig. 4 is a corresponding horizontal section.

In the' drawings, il designates the side wall of the tank, 32 its bottom, and 33 its iixed roof, which is of the ordinary type.

On the liquid contained in this tank. iloats a Huid-tight ring Srl, the outer edge 34a of which. constitutes the edge of a. wedge, the upper face 35 of which is downwardly inclined from the interior towards the exterior of the ring, and the lower face 36 of which is inclined in the reverse direction. The ring is loaded in such a way that the edge 34a is approximately at they levelof the liquid.

rlhe external diameter of this ring 34 is slightly smaller than that of the minimum internal diameter which the tank il may have at any point of its height.

Small spheres 3l float on the surface of the liquid between the ring and the inner wall of the tank, these spheres being of relatively small diameter, for instance of the order of 1 to 3 centimeters, and beingmad'e of any suitable mate rial, such as wood, metal, Celluloid, etc.

The weight of these spheres is such (owing eventually to the fact that they are suitably loaded) that they are partially immersed, preferably midway of their height,- and they are suiiicient in number so that, at the largest inner diameter of the tank, they cover the entire free surface of the liquid between the ring and the wall 8 by being in contact with each other.

"When, during its vertical displacement, the floating roof is at a point of the tank the inner diameter of which has a value lower than the maximum value above mentioned (see the part in dot and dash lines at the top of Fig. 3), the spheres 3l move, relatively to the ring 3K3, inwardly of the latter, so that the spheres adjacent e to the edge 34a are compelled, either to ride up the upper wall 35 of the ring, as indicated at tlmor to pass under the lower wall 36, as indicated at 31h.

The weight of the spheres 31a, lifted out of 10 the liquid, and the hydrostatic thrust exerted on the spheres 31h, completely immersed in this liquid, conjointly with the inclination of the faces 35, St, exert on the spheres which still float a radial stress directed towards the wail t.

The spheres-'are thus always maintained in contact with each other and the greatest possible portion of the free surface of the liquid is covered. v

If lthe spheres are immersed exactly midway of their height, and regularly arranged, in stable equilibrium, in .contact with each other, that is to say, if each. of them is in contact with six other spheres at six points of its great horizontal circle, it is easy to calculate that the covered surface of the liquid, that is to say the sum of Y the equatorial sections of the spheres, represents about 90% of the total surface on which they oat.

If the spheres assume a position of unstable equilibrium, such that each of them is in contact with four other spheres only, the covered surface still represents about 80% of the total surface.

Even in the most unfavourable case, this device covers therefore a much more important fraction of the free surface of the liquid between the tank and the edge of the iioating roofl than ordinary devices.

instead of a single layer of spheres immersed midway of the liquid, several layers might be used, the spheres being 'in this case of smaller diameter and less dense, so that one sphere plunges in the liquid according to a fraction only of its radius, the lower spheres being pari tially immersed in the liquid by the weight of the upper spheres.

instead of spheres, bodies of any shape can be used, for instance ovoids or ellipsoids the great axis of. which is held vertical by suitably loading them.

IThe surface of the liquid within the ring 34 is covered by a foil or'impervious illm i, in contact, throughout the extent of its lower face, with the liquid on which it rests, and secured in a fluid-tight manner by its edge to the ring 34.

The foil or film can be made of any suitable material, such as aluminium foil, cellulose products of the celloidine type, thin stainless sheet metal, celluloid, canvas or paper waterproofed, or metallized, or reinforced by wire gauze, these various elements being utilizable either separately. or combined in any suitable manner.

This film I being adapted to prevent any contact between the volatile liquid and the atmosphere and being very flexible owing to its small thickness, it is necessary to avoid the formation, between the film and the liquid, of pockets Vof gas which, dissolved in the liquid, might evolve therefrom; for that purpose, at several points of the film surface, orifices I5 are provided, each of these orifices communicating with the atmosphere through a small vertical tube I 6, the height of which is suiiicient for preventing the liquid from passing above the film I.

For allowing to clean the bottom ofthe tank,

to effect repairs of the above mentioned device,

etc., a metal grating is provided under the said device, this grating being preferably made of section members and freely resting on the bot- The said grating comprises a series of bars 38 secured to a circular angle iron 39, the diameter of which is approximately equal to that of the ring 34.

The grating is attached, at a number of points of the angle iron 39, to vertical cables or bars 40 which pass through the ring 34 in conduits 34h provided in the latter and suitably devised for preventing the passage of the liquid, and through the roof 33, through fluid-tight orifices; these cables or bars can be lifted from the exterior by any suitable means: winch, or a nut control 4I for instance.

When the tank is empty, the ring 34 and film I rest on the grating (see the part shown in dot and dash lines at the bottom of Fig. 3) and it is possible, when a job hm to be effected, to lift the entire structure, by means of the above device, to the required extent for allowing to have access between the bottom 32 and the floating roof.

It is to be noted that during normal working conditions, these cables or bars 40 serve as guides along which the oating roof slides parallel to the walls.

When the grating is raised, the spheres 31 remain on the bottom 32; they are prevented from scattering by an angle iron 42 secured on .this bottom, concentric with the side wall 8.

For preventing suction at the outlet, or pressure at the inlet from breaking the thin lm I or from displacing the spheres 31, each orifice, such as 26, will be concealed by a sheet metal plate 28, secured at a sufficient distance in front of this orifice, for breaking the force of the stream.

It is to be noted that, as the ring 34 is of small height, for instance 4 to 5" above and below the level of the liquid, this floating roof practically operates until it comes in contact with the fixed roof, on the one hand, and with the bottom of the tank, on the other hand.

Moreover, the film rests, throughout its area on the liquid,t or, when the tank is empty, it is supported by the grating; it is not therefore subjected to any stress, and it can be made of very small thickness, this rendering the device very economical.

The form of construction described above solely by way of example, can of course be modiaoaasos fied in its details in any suitable manner, without thereby departing from the scope of the lnvention; in particular, concerning the arrangement of the floating roof and of the device allowing to raise it, any suitable arrangements can be provided for maintaining the spheres, or floating bodies of any other shape, in contact with each other; for instance, instead of giving the edge of the ring 34 the shape of a wedge, it might be made in the shape of a truncated cone or pyramid having a sufcient height above and below the surface of the liquid in order that, when the inner diameter of the tank diminishes, the spheres are simply lifted above the liquid if the said truncated cone flares downwardly, or plunged in this liquid if it dares upwardly. The profile of the ring 34 can also be given an ogival shape or another rounded shape. In order to cover the most important fraction possible of the free surface of the liquid, spheres of different diameters can be used, the proportions of spheres of different diameters being determined so as to provide the best covering of this surface.

Having now particularly described the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:-

1. In a tank adapted to contain a liquid, the combination of a floating roof and of a series of bodies generated by a surface of revolution, so loaded as to float on the liquid with their axes of revolution vertical, their plane of notation being that of their maximum horizontal section, these bodies being in suiilcient number for forming, by being in contact with each other in float ing position, a continuous layer of a single thickness on the free surface of the liquid between the edge of the oating roof and the inner wall of the tank, at the place where the area of the section of this tank is maximum.

2. In a tank adapted to contain a liquid, the combination of a floating roof, of a series of bodies adapted to oat at the surface of the liquid, these bodies being in sufficient number for forming, by being in contact with each other in floating position a layer of a single thickness, at least the free surface of the liquid between the edge of the floating roof and the inner wall of the tank, at the place where the area of the inner section of this tank is maximum, at the periphery of the floating roof, and of a wall inclined downwardly and from the interior towards the exterior of the floating roof, the floating bodies being adapted to slide on this wall when, in position of otation, they are subjected to a horizontal stress directed from the exterior towards the interior of the roof.

3. In a tank adapted to contain a liquid, the combination of a floating roof, of a series of bodies adapted to float at the surface of the liquid, these bodies being in sufficient number for forming, by being in contact with each other in position of dotation a layer of a single thickness, at least the free surface of the liquid between the edge of the floating roof and the inner wall of the tank, at the place where the area of the inner section of this tank is maximum, at the periphery of the fioating roof, and of a wall inclined upwardly and from the interior towards the exterior of the floating roof, the, floating bodies being adapted to slide under this wall when, in position of flotation, they are subjected towards the interior of the roof.

4. In a tank adapted to contain a liquid, the combination of a floating roof, of a series of bodies adapted to float at the surface of the liquid, these bodies being in suiilcient number for forming, by being in contact with each other in position of notation a layer of a single thickness, at least the free surface of the liquid between the edge of the iloating roof and the inner wall of the tank, at the place where the area of the inner section of this tank is maximum, at the periphery of the floating roof, the border of said floating roof having, in diametral section, the shape of a wedge open towards the interior of the floating roof, this roof being so adapted that the apex of this wedge is approximately located at the level of the surface of the liquid in position of flotation, and the noating bodies being adapted to slide along the faces of the wedge when in position of notation, they are subjected to a horizontal stress directed from the exterior towards the interior of-the roof.

5. In a tank adapted to contain a liquid the combination of a floating roof, of a series of bodies adapted to float at the surface o! the liquid, these bodies being in sumcient number for forming, by being in contact with each other in position of flotation a layer of a single thickness, at least the tree surface of the liquid between the edge of the iloating roof and the inner wall or the tank, at the place where the area of the inner section of this tank is maximum, and, at the bottom of the tank, of a projecting ledge adapted to hold the iloating bodies between it and the side wall of the tank when the latter is empty.

6. In a tank adapted to contain a liquid, a floating roof comprising a frame adapted to iloat on the liquid and a thin foil made of a flexible material impervious to the liquid of the tank and inert relatively to this liquid, this thin foil being secured to 'the frame in a duid-tight manner and adapted to be in contact with the surface of the liquid Vthroughout the extent of its lower face in position of ilotation and means for automatically evacuating the gases generated under said thin foil.

7.111 a tank adapted to contain a liquid, a floating roof comprising a frame adapted to iloat on the liquid and a thin foil made of a ilexible material impervious to the liquid of the tank and inert relatively to this liquid, this thin foil being securedto the frame in a uuid-tight manner, adapted to be in contact with the surface ofthe liquid throughout the extent of its lower face in position of notation, and perforated with small gas outlet holes, and, on these holes, 5

tubes substantially vertical and having a sumcient height for preventing the liquid from passing through the holes. above the floating roof. l

8. In atank adapted to contain a liquid, a

iloating roof comprising a frame adapted to iloat l0 l duction of eddies by contact with the said thin 20 f foil.

9. In a tank adapted to contain a liquid, a floating roof comprising a frame adapted to float on the liquid and athin foil made of a material impervious to the liquid of the tank and inert 25' relatively to this liquid, this thin foil being secured to the frame in a iluid-tight manner and adapted to be in contact with the surface of the liquid throughout the extent of its lower face in position of flotation, a movable support for 30 the said iloating roof and arranged under the latter, and 4means for vertically moving the said support in the tank.

l0. In a tank adapted to contain a liquid, a floating roof comprising a frame adapted to oat 35 on the liquid and a thin foil made of a material impervious to the liquid of the tank and inert relatively to this liquid, this thin foil being secured to the frame in a duid-tight manner and v adapted to be 1n contact with me surface of the 40 liquid throughout the extent of its lower face in position of notation, a movable support for the said iioating roof and arranged under the latter, guides parallel to the side walls of the tank, having their lower ends attached to the said support, and along which the roof is adapted to slide, these guides passing through the fixed roof of the tank through duid-tight orifices, and means for longitudinally moving the said guides. w

SERVN GEORGES CANTAC'UZENE. 

